Modern processors operate at very high processing rates and in so doing generate large amounts of heat which must be dissipated to prevent overheating of the processor which can result in damage to the processor. Generally, a fan is used to dissipate the heat and prevent overheating of the processor. In order to avoid fan noise and waste of energy in operating the fan itself, it is desired to control the speed of the fan according to the required extent of heat dissipation. It has been suggested to control the fan speed in accordance with the power consumption of the processor.
However, determining the power consumption of the processor is not always simple and in some cases it is desirable to control the fan operation without knowledge of the power consumption of the processor.
The decision on the speed of the fan in the relatively low power consumption range is governed by two competing considerations. On the one hand, it is desired to use as low as possible fan speed in order to reduce power consumption of the fan. On the other hand, it is desired to make sure that the temperature of the processor does not exceed a temperature threshold.